Properly handled combustion boilers can be a very efficient source of energy. The task however can be quite complicated, when taking possible anomalies into account and of course the impact on our environment. That’s why the proper analysis of the exhaust gases and then control of the burning cycle can bring not only cost savings but also safety and environment friendly results.
Combustion Boiler Control
Let’s take a look at the system of six industrial boilers. Each boiler can have up to 8 analogue inputs, one analogue output and some digital IO points. All data needs to be scaled and should have min/max alarms. Most of the data measured needs to be calculated in different engineering units, depending on the fuel used in the burner. The data then needs to be logged and stored for future reference and analysis.
Based on the system requirements, Horner has developed a solution consisting of the XL6e as a main controller, together with multiple SmartMod IO modules (Modbus RTU), one module per boiler. Controller uses the Micro SD card for all the necessary datalogging and because of the embedded Ethernet port, the whole application can be monitored and controlled via Web Server or Envision RV.
During the first stage of implementation, our XL6e was used as an exhaust gases analyser. It was achieved by multiple probes connected to each SmartMod IO measuring level of gases like CO, CO2 or NO, a pressure and a temperature (up to 8 signals). The controller was scaling, calculating and storing the values on the flash memory. This data was crucial to determine whether the process was environment safe or not. The second phase was embedding the control algorithm into the burner working cycle and dosing the oxygen input.
The Cscape configuration file consists of:
- Hardware configuration (XL6e + SmartMod I/O)
- Scaling procedures (Logic Modules -> Main -> Scaling)
- Finding Min/Max Values (Logic Modules -> Main -> Min_and_Max)
- Control procedure (Logic Modules -> Main -> Control)
- Handling Alarms (Logic Modules -> Alarms)
- Datalog configuration (menu Program -> Datalog Configuration)
- Application Screens (Overview + Alarm screens)
(Cscape 9.20 SP1 or higher needed)
A Horner solution was chosen because of its flexibility powerful datalogger and several remote access options. Also the working conditions (wide temp. range, dust and electrical noise) were too harsh for some of the competition. It was also important for the maintenance team to be able to easily see what’s going on and quickly determine the level of pollution (hence colourful, good quality screen).
The benefits for the plant manager are quite obvious. Proper oxygen content control optimizes the air/fuel ratio which equals energy savings. The process itself becomes safer, because whenever an anomaly is detected, the burning cycle can be corrected. To sum up: correct combustion means money savings and safer and cleaner plants.